spec-dvi.mkii / last modification: 2020-01-30 14:15
%D \module
%D   [       file=spec-dvi,
%D        version=1996.01.25,
%D          title=\CONTEXT\ Special Macros,
%D       subtitle=Generic \TEX\ Solutions,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

%D \macros
%D   {dostartobject,
%D    dostopobject,
%D    doinsertobject}
%D
%D Reuse of object is not supported by the \DVI\ format. We
%D therefore just duplicate them using boxes.

\setjobsuffix{dvi} % can be overloaded in other spec's

\startspecials[tex]

\newbox\DVIobjects \newcounter\DVIobjectcounter

\definespecial\dostartobject#1#2#3#4#5%
  {\setbox\nextbox\vbox\bgroup
     \def\dodostopobject
       {\egroup
        \doglobal\increment\DVIobjectcounter
        \global\setbox\DVIobjects\vbox
          {\offinterlineskip
           \forgetall
           \unvbox\DVIobjects
           \setbox\nextbox\hbox{\box\nextbox}%
           \wd\nextbox\zeropoint
           \dp\nextbox\zeropoint
           \ht\nextbox\onepoint
           \allowbreak
           \box\nextbox}%
        \dosetobjectreference{#1}{#2}{\DVIobjectcounter}}}

\definespecial\dostopobject
  {\dodostopobject}

\definespecial\doinsertobject#1#2%
  {\bgroup
   \dogetobjectreference{#1}{#2}\DVIobjectreference
   \splittopskip\zeropoint
   \setbox0=\copy\DVIobjects
   \dimen0=\DVIobjectreference\onepoint
   \advance\dimen0 -\onepoint
   \setbox2\vsplit0 to \dimen0
   \ifdim\ht0>\onepoint
     \setbox0\vsplit0 to \onepoint
   \fi
   \unvbox0
   \setbox0\lastbox
   \hbox{\unhbox0}% the \hbox is really needed!
   \egroup}

%D \macros
%D   {dosetposition,
%D    dosetpositionwhd,
%D    dosetpositionplus}
%D
%D The next specials only identify a position. It is up to
%D a \DVI\ postprocessing utility to merge the right commands
%D into the utility file. Since in \CONTEXT, we only deal
%D with relative positions, the reference point is not so
%D important.
%D
%D The postprocessor should translate the specials into
%D commands and append these to \type {jobname.tuo} using the
%D format:
%D
%D \starttyping
%D \pospxy    {identifier}{page}{x}{y}
%D \pospxywhd {identifier}{page}{x}{y}{w}{h}{d}
%D \pospxyplus{identifier}{page}{x}{y}{w}{h}{d}{list}
%D \stoptyping
%D
%D The postprocessor should, of course, provide the \type
%D {page}, \type {x}, and \type {y} values.

%D Now in spec-mis.tex:

% \definespecial\dosetposition#1%
%   {\special{pos:pxy "#1"}}
%
% \definespecial\dosetpositionwhd#1#2#3#4%
%   {\special{pos:pxywhd "#1" #2 #3 #4}}
%
% \definespecial\dosetpositionplus#1#2#3#4#5%
%   {\special{pos:pxyplus "#1" #2 #3 #4 #5}}

%D The next special tells the position postprocessor what
%D page dimensions were used.

%D Also in spec-mis.tex:

% \let\flushDVIpositionpapersize\relax
%
% \definespecial\dosetpositionpapersize#1#2%
%   {\xdef\flushDVIpositionpapersize%
%      {\special{pos:papersize \number#1 \number#2}%
%       \noexpand\installprogram{dvipos -o \jobname.tuo \jobname.dvi }%
%       \global\noexpand\let\noexpand\flushDVIpositionpapersize\relax}}
%
% \prependtoksonce \flushDVIpositionpapersize \to \everyshipout

\stopspecials

\endinput